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s390/ism: clear dmbe_mask bit before SMC IRQ handling

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[ Upstream commit 007b656851 ]

SMC-D stress workload showed connection stalls. Since the firmware
decides to skip raising an interrupt if the SBA DMBE mask bit is
still set, this SBA DMBE mask bit should be cleared before the
IRQ handling in the SMC code runs. Otherwise there are small windows
possible with missing interrupts for incoming data.
SMC-D currently does not care about the old value of the SBA DMBE
mask.

Acked-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ursula Braun 2018-11-12 17:06:12 +01:00 • committed by Greg Kroah-Hartman
commit b65fa443e5
1 changed files with 1 additions and 1 deletions
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2
drivers/s390/net/ism_drv.c
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@ -415,9 +415,9 @@ static irqreturn_t ism_handle_irq(int irq, void *data)
break;
clear_bit_inv(bit, bv);
ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0;
barrier();
smcd_handle_irq(ism->smcd, bit + ISM_DMB_BIT_OFFSET);
ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0;
}
if (ism->sba->e) {